Improving qubit coherence using closed-loop feedback

Abstract

Superconducting qubits are a promising platform for building a larger-scale quantum processor capable of solving otherwise intractable problems. In order for the processor to reach practical viability, the gate errors need to be further suppressed and remain stable for extended periods of time. With recent advances in qubit control, both single- and two-qubit gate fidelities are now in many cases limited by the coherence times of the qubits. Here we experimentally employ closed-loop feedback to stabilize the frequency fluctuations of a superconducting transmon qubit, thereby increasing its coherence time by 26\% and reducing the single-qubit error rate from $(8.5\pm 2.1)\times 10^{-4}$ to $(5.9\pm 0.7)\times 10^{-4}$. Importantly, the resulting high-fidelity operation remains effective even away from the qubit flux-noise insensitive point, significantly increasing the frequency bandwidth over which the qubit can be operated with high fidelity. This approach is helpful in large qubit grids, where frequency crowding and parasitic interactions between the qubits limit their performance.

15 pages, 7 figures

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Cited by in corpus (18)

• Overcoming I/O bottleneck in superconducting quantum computing: multiplexed qubit control with ultra-low-power, base-temperature cryo-CMOS multiplexer
• Systematic study of High $E_J/E_C$ transmon qudits up to $d=12$
• Robust Quantum Gates against Correlated Noise in Integrated Quantum Chips
• A superconducting qubit with noise-insensitive plasmon levels and decay-protected fluxon states
• Real-time two-axis control of a spin qubit
• Real-time feedback protocols for optimizing fault-tolerant two-qubit gate fidelities in a silicon spin system
• Physics-informed tracking of qubit fluctuations
• Passive and active suppression of transduced noise in silicon spin qubits
• Dephasing in Fluxonium Qubits from Coherent Quantum Phase Slips
• Qubit fidelity under stochastic Schrödinger equations driven by colored noise
• Prolonging a discrete time crystal by quantum-classical feedback
• Beating the Ramsey limit on sensing with deterministic qubit control
• Efficient Qubit Calibration by Binary-Search Hamiltonian Tracking
• A quantum register using collective excitations in a Bose-Einstein condensate
• Accessing the Full Capabilities of Filter Functions: A Tool for Detailed Noise and Control Susceptibility Analysis
• Noise cross-correlations from single-shot measurements
• Iterative Adaptive Spectroscopy of Short Signals
• Characterization and cancellation of power-line-induced motional-mode frequency noise in a trapped-ion system